The possible adverse effects on performance of an antihistamine and alcohol were evaluated in non-residential subjects without histories of drug abuse, other than cigarette smoking. The study involved the use of strategies recommended by the Joint Triservices Working Group (Army Contract) to assess behavioral (i.e., cognitive) performance. Measures included the standard Army Performance Assessment Battery (PAB), prototypic portions of the Unified Triservices Battery (UTC PAB), critical flicker fusion, and mood, as well as cardiovascular and other basis physiologic variables. Preliminary analysis of data from the first study suggest that alcohol and chlorpheneramine produced dose-related effects on several self-report measures and mixed effects on performance across measures. These initial results suggest that the PAB is less sensitive compared to the Digit Symbol Substitution Task with respect to the level of performance disruption by alcohol or chlorpheramine. Subsequently, a new protocol compared a non-centrally acting antihistamine (terfenadine) to a centrally acting one (diphenhydramine) as well as to the benzodiazepine, triazolam. Data collected has been completed and the results are presently being analyzed to prepare a report for publication. This was the final study in the series of those conducted in collaboration with the Joint Triservices Working Group (Army Contract).